CO Hydrogenation over functionalized AlMCM-41 materials and ZSM-11/5 zeolites as catalysts

Smili, B.; Sakmeche, M.; Belhakem, A.; Belgacem, L.; Tabti, C.

doi:10.30495/ijc.2022.1956221.1928

Original Article

CO Hydrogenation over functionalized AlMCM-41 materials and ZSM-11/5 zeolites as catalysts

Authors

Laboratory of Energy Environment and Information System (LEEIS), Department of Material Sciences, Faculty of Sciences and Technology, University of Adrar, National Highway No. 06. Adrar 01000, Algeria.
Laboratory of Saharan natural resources (LRNS), Department of hydrocarbons and renewable energies, Faculty of Science and Technology. University of Adrar, National High way No. 06. Adrar 01000, Algeria.
Department of Chemistry, University of Mostaganem, B.P 1001, 27000 Mostaganem, Algeria
Research center in industrial technologies CRTI, Cheraga 16014, Algiers, Algeria

Abstract

We studied the reaction in which carbon monoxide is converted to hydrocarbons, and investigated the behaviors and the combination system of catalysts exchanged with platinum and ammonium ions. Experiments were conducted at 1.2 MPa, 523K, and CO/H₂=1 ratio. The structure and the texture of the catalysts, assessed by XRD, BET/BJH, and SEM, exhibited a microporosity for ZSM-5/11 and a micro/mesoporosity for AlMCM-41, which implies a direct effect on the catalytic properties of these materials. The conversions obtained were 60%, 55%, and 50% for Ptⁿ⁺/H⁺-catalysts, Pt^n+-catalysts, and H⁺-catalysts respectively. Such conversions could be attributed to the good acidity resulting from the simultaneous presence of Ptn⁺/H⁺ at different oxidation states of platinum, which was revealed by XANES PtL_III analysis, and their uniform dispersion within the inner surface and its grain size average conducted by the titration of adsorbed H₂-O₂. FTIR analysis showed a better distribution of acid sites for bi-exchanged catalysts over mono-exchanged ones, which resulted in a good catalytic activity. These results suggest a strong correlation between the high selectivity of light hydrocarbon products, the ions, and the catalyst types. These differences depended mainly on the facility of forming different products, such as n/iso-alkanes and alkenes. Skeletal isomerization was the main transformation observed on exchanged catalysts, particularly those with Ptⁿ⁺/H⁺ ions. A deactivation process of catalysts, versus time-on-stream, begins after 70 minutes, especially for combined exchanged materials.

Highlights

CO conversion over Ptn⁺/H⁺-catalysts is a good process for obtaining light products.
Behaviours of AlMCM-41, ZSM-(5and11) functionalized as bi-functional catalysts.
Good acidities due to the presence of Ptn⁺/H⁺ ions in surface of catalysts.
XANES PtLIII and titration H₂-O₂ are good techniques for characterization of Pt spices.
Ptn⁺/H⁺-catalyst have a good catalytic performances than H⁺-catalyst.